Of Interest: For the month of September, MESSENGER images of the double-ring basin Rachmaninoff are being featured by the International Association of Geomorphologists (IAG) as the planetary geomorphology image of the month. The enhanced-color image shown here is one of those featured images and highlights differences in reflectance, color, and structure between the smooth plains within the basinís inner ring and the surrounding surface. MESSENGER team members have documented evidence that these interior smooth plains are products of relatively young volcanism, the youngest documented on Mercury to date. Whereas pre-MESSENGER interpretations were that volcanism on Mercury ended early in the planetís history, MESSENGERís images of Rachmaninoff reveal that some volcanism extended well beyond that time, probably into the second half of Solar System history. Visit the IAG planetary geomorphology website to read more.